Full melting detection method for single crystal furnace

Abstract

The invention provides a full melting detection method for a single crystal furnace. The full melting detection method comprises the following steps: S1, controlling a main heater and a bottom heater to heat a crucible added with a silicon material; s2, after a first melting time interval, an image collector is controlled to collect melt ratio information of the silicon material for multiple times in a first detection time period, and when it is determined that the proportion of the number of the melt ratio larger than or equal to a first melt ratio threshold to the total number of times of detection in the first detection time period is larger than or equal to a first proportion threshold, a first temperature adjusting strategy is executed; ..., after the Nth melting time, the image collector is controlled to collect the melt ratio information of the silicon material for multiple times in the Nth detection time period, when it is determined that the proportion of the number of the melt ratio larger than or equal to the Nth melt ratio threshold to the total number of times of detection in the Nth detection time period is larger than or equal to the Nth proportion threshold, the Nth temperature adjusting strategy is executed, N is an integer larger than or equal to 2, and N is an integer larger than or equal to 2. The Nth melt ratio threshold value is 81%-100%, and the Nth ratio threshold value is 90%-100%. The method can improve the automation degree of monocrystalline silicon production.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal manufacturing, and in particular to a single crystal furnace full melting detection method. Background Art

[0002] In the process of direct-pull single-crystal silicon production, multiple process steps are required from polysilicon material to single-crystal silicon rods. In the process steps of re-injection, material treatment, seeding, shoulder release, shoulder rotation, equal diameter and finishing, the state of the crystal and the molten silicon liquid level need to be monitored. In actual production, the timing of closing the bottom heater of the single crystal furnace has a very important impact on single crystal pulling. If the bottom heater is turned off too early, the silicon material cannot be fully melted. If the bottom heater is turned off too late, the furnace will maintain a high-temperature heating state for a long time, aggravating the reaction between the quartz crucible and the silicon material. The quartz crucible is heated at high temperature for a long time, resulting in a reduction in the service life of the crucible, causing serious accidents such as silicon leakage. At present, it is necessary to manually observe the melting of silicon materials in the furnace with the naked eye, judge the state of the furnace, and judge the timing of operations such as closing the bottom heater and lowering the water cooling screen based on experience. This greatly increases the labor intensity of workers and there are potential accidents caused by human factors. Summary of the invention

[0003] In view of this, the present invention provides a single crystal furnace full melting detection method, which can automatically judge the melting condition of silicon material.

[0004] In order to solve at least one of the above technical problems, the present invention adopts the following technical solutions:

[0005] A single crystal furnace full melt detection method according to an embodiment of the present invention is applied to a single crystal furnace, wherein the single crystal furnace comprises a crucible, a main heater, a bottom heater, an image collector and a controller, wherein the image collector is arranged on a furnace cover of the single crystal furnace and is located above the crucible. The method comprises:

[0006] S1, the controller controls the main heater and the bottom heater to heat the crucible after adding silicon material;

[0007] S2, after the first melting time, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times in the first detection period, and the information is transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the first detection period is greater than or equal to the first melt ratio threshold value accounts for a proportion of the total number of detections in the first detection period that is greater than or equal to the first ratio threshold value, the first temperature adjustment strategy is executed;

[0008] ...,

[0009] After the Nth melting time, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times in the Nth detection period, and the information is transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the Nth detection period is greater than or equal to the Nth melt ratio threshold and the proportion of the total number of detections in the Nth detection period is greater than or equal to the Nth proportion threshold, the Nth temperature adjustment strategy is executed, wherein N≥2, and N is an integer, the Nth melt ratio threshold is 81%-100%, and the Nth proportion threshold is 90%-100%.

[0010] In one embodiment of the present invention, the single crystal furnace further includes a water cooling screen disposed below the image collector, and the first temperature adjustment strategy, ..., and the Nth temperature adjustment strategy all include adjusting at least one of the following parameters:

[0011] The power of the main heater, the power of the bottom heater, the speed of the crucible and the descent height of the water cooling screen.

[0012] In one embodiment of the present invention, N=4, the first melt ratio threshold is 10%-15%, the second melt ratio threshold is 25%-35%, and the third melt ratio threshold is 55%-75%;

[0013] The first ratio threshold is 60%-70%, the second ratio threshold is 70%-80%, and the third ratio threshold is 85%-90%.

[0014] In one embodiment of the present invention, the first melting time is 5-15 minutes, the second melting time is 1-3 minutes, the third melting time is 1-3 minutes, and the fourth melting time is 1-3 minutes.

[0015] In one embodiment of the present invention, the first detection period is 100-140 seconds, the second detection period is 80-120 seconds, the third detection period is 30-60 seconds, and the fourth detection period is 30-60 seconds.

[0016] In one embodiment of the present invention, the first temperature strategy includes:

[0017] Controlling the main heater and the bottom heater by a controller to heat the crucible with a first main heating power and a first bottom heating power respectively;

[0018] Controlling the water cooling screen to descend from the initial position to the first position at a first speed through a controller;

[0019] The crucible is controlled by a controller to rotate at a first rotation speed.

[0020] In one embodiment of the present invention, the second temperature strategy includes:

[0021] Controlling the water cooling screen to descend from a first position to a second position at a first speed by a controller;

[0022] Controlling the main heater and the bottom heater by the controller to continue to heat the crucible with a first main heating power and a second bottom heating power respectively;

[0023] The crucible is controlled by a controller to rotate at a first rotation speed.

[0024] In one embodiment of the present invention, the third temperature strategy includes:

[0025] Controlling the water cooling screen to descend from the second position to the third position at a first speed by a controller;

[0026] Controlling the main heater and the bottom heater by the controller to continue to heat the crucible with the first main heating power and the third bottom heating power respectively;

[0027] The crucible is controlled by a controller to rotate at a second rotation speed.

[0028] In one embodiment of the present invention, the fourth temperature strategy includes:

[0029] Controlling the water cooling screen to descend from the third position to the fourth position at the second speed by the controller;

[0030] Controlling the main heater and the bottom heater by the controller to continue to heat the crucible with the first main heating power and the fourth bottom heating power respectively;

[0031] The crucible is controlled by a controller to rotate at a third speed.

[0032] Further, in step S1, the power of the main heater and the power of the bottom heater are both 85kw-96kw;

[0033] The first speed is 150-250 mm / min, and the second speed is 100-150 mm / min;

[0034] The first position is a position where the water cooling screen is 200-250 mm away from the silicon material liquid surface, the second position is a position where the water cooling screen is 150-200 mm away from the silicon material liquid surface, the third position is a position where the water cooling screen is 100-150 mm away from the silicon material liquid surface, and the fourth position is a position where the water cooling screen is 0-100 mm away from the silicon material liquid surface;

[0035] The first main heating power is 85kw-96kw, the first bottom heating power is 85kw-96kw, the second bottom heating power is 45kw-55kw, the third bottom heating power is 0kw-5kw, and the fourth bottom heating power is 0kw-5kw;

[0036] The first rotation speed is 1-2 rpm, the second rotation speed is 2-3 rpm, and the third rotation speed is 3-5 rpm.

[0037] The above technical solution of the present invention has at least one of the following beneficial effects:

[0038] The single crystal furnace full melting detection method of the present invention collects the melting ratio information of the silicon material in the crucible for multiple times in the corresponding detection period, and when it is determined that the number of silicon material melting ratios greater than or equal to the predetermined melting ratio threshold in the detection period accounts for a ratio greater than or equal to the predetermined ratio threshold of the total number of detections in the detection period, a predetermined temperature adjustment strategy is executed. And so on until after the Nth melting time interval, when it is determined again during the detection that the number of silicon material melting ratios greater than or equal to 81%-100% in the Nth detection period accounts for a ratio greater than or equal to 90%-100% of the total number of detections in the Nth detection period, the Nth temperature adjustment strategy is executed. Thus, automated full melting detection and temperature adjustment are realized in the single crystal production process, thereby reducing the dependence on the experience of manual single crystal furnace full melting detection, effectively reducing labor costs, improving production efficiency, and avoiding safety accidents caused by human errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Flow chart of a method for detecting full melting of a single crystal furnace in an embodiment of the present invention;

[0040] Figure 2 This is a flow chart when N is 4 in the single crystal furnace full melt detection method in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0042] To facilitate the understanding of the technical solution of the present invention, the technical problem to be solved by the present invention is first described.

[0043] In the prior art, it is necessary to manually judge the melting condition of silicon materials in the single crystal furnace, and judge the timing of shutting down the bottom heater, lowering the water cooling screen, etc. based on experience. In this way, the labor intensity is high, and the crucible is likely to be in a high temperature state for a long time, resulting in a reduced crucible service life and a safety hazard of silicon leakage. In addition, it is impossible to achieve a unified standard for manual judgment of the melting condition of silicon materials, which affects the quality of the welding and lead-out processes and greatly reduces the crystallization rate.

[0044] To solve the above technical problems, the present invention provides a method for detecting full melting of a single crystal furnace. Specifically, the single crystal furnace of an embodiment of the present invention includes a crucible, a main heater, a bottom heater, an image collector and a controller. Among them, the image collector is arranged on the furnace cover of the single crystal furnace and is located above the crucible, the image collector can be a detection camera, the crucible is arranged in the furnace body of the single crystal furnace, and is used to accommodate silicon material, and the bottom of the crucible is provided with a rotating shaft for driving the crucible to rotate. The bottom heater is arranged below the crucible, the main heater surrounds the outside of the crucible, and the bottom heater and the main heater are used to heat the crucible respectively to melt the silicon material in the crucible. The controller is electrically connected to the image collector, the rotating shaft, the bottom heater and the main heater respectively. The controller can detect the melting of the silicon material in the single crystal furnace through the image collector, that is, detect the melting ratio information of the silicon material, and control the heating power of the bottom heater and the main heater respectively according to different melting ratio information, and control the rotation speed of the crucible at the same time, thereby reducing the dependence on the experience of full melting detection of the artificial single crystal furnace, realizing automated single crystal silicon production, and effectively improving production efficiency.

[0045] First, a single crystal furnace full melt detection method according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0046] Figure 1 FIG. 4 is a flow chart showing a method for detecting full melting of a single crystal furnace provided by an embodiment of the present invention. Figure 1 As shown, the single crystal furnace full melt detection method of the embodiment of the present invention comprises the following steps:

[0047] S1, controlling the main heater and the bottom heater through the controller to heat the crucible after adding the silicon material;

[0048] S2, after the first melting time, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times in the first detection period, and the information is transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the first detection period is greater than or equal to the first melt ratio threshold value accounts for a proportion of the total number of detections in the first detection period that is greater than or equal to the first ratio threshold value, the first temperature adjustment strategy is executed;

[0049] ...,

[0050] After the Nth melting time, the melt ratio information of the silicon material in the crucible is collected multiple times in the Nth detection period by controlling the image collector, and transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the Nth detection period is greater than or equal to the Nth melt ratio threshold value accounts for the total number of detections in the Nth detection period. The Nth temperature adjustment strategy is executed, wherein N≥2, and N is an integer, the Nth melt ratio threshold value is 81%-100%, and the Nth ratio threshold value is 90%-100%. Among them, the Nth melt ratio threshold value can be 81%, 85%, 90%, 95% or 100%, etc., and the Nth ratio threshold value is 90%-100%, for example, it can be 90%, 93%, 95%, 98% or 100%, etc.

[0051] In this embodiment, after each interval of a certain melting time, the melting ratio information of the silicon material in the crucible can be collected multiple times in the corresponding detection period by controlling the image collector, and transmitted to the controller in real time. When the controller determines that the number of the melting ratio of the silicon material in the detection period is greater than or equal to the predetermined melting ratio threshold and the proportion of the total number of detections in the detection period is greater than or equal to the predetermined proportion threshold, the predetermined temperature adjustment strategy is executed to adjust the temperature of the crucible and the silicon material in the crucible. And so on, until after the interval of the Nth melting time, the melting ratio information of the silicon material in the crucible is collected multiple times in the Nth detection period by controlling the image collector again, and the controller determines that the number of the melting ratio of the silicon material in the Nth detection period is greater than or equal to 81%-100% and the proportion of the total number of detections in the Nth detection period is greater than or equal to 90%-100%, that is, when the silicon material is in a fully molten state, the Nth temperature adjustment strategy is executed to prevent the silicon material temperature from continuing to rise. As a result, automated full melt detection and temperature adjustment are achieved in the single crystal production process, thereby reducing the dependence on the experience of full melt detection in manual single crystal furnaces. This effectively reduces labor costs, improves production efficiency, and avoids safety accidents caused by human errors.

[0052] In one embodiment of the present invention, the single crystal furnace also includes a water-cooled screen disposed below the image collector and opposite to the crucible, and the first temperature adjustment strategy, ..., the Nth temperature adjustment strategy all include adjusting at least one of the following parameters: the power of the main heater, the power of the bottom heater, the rotation speed of the crucible and the descent height of the water-cooled screen.

[0053] Specifically, the bottom heater is arranged below the crucible, and the main heater is arranged around the crucible. The bottom heater and the main heater are used to heat the crucible from below the crucible and around the crucible, respectively. Thus, by adjusting the power of the main heater and the power of the bottom heater, the temperature of the crucible and the silicon material in the crucible can be adjusted. By adjusting the rotation speed of the crucible, the temperature uniformity of the silicon material can be improved, the temperature gradient can be reduced, and local overheating or overcooling can be avoided. In addition, by adjusting the descending height of the water-cooling screen, the heat radiation received by the crucible and the surface of the molten silicon material can be adjusted, so as to more accurately control the temperature of the silicon material and avoid overheating. In addition, since the water-cooling screen is lowered, the detection range of the image collector can be expanded, which is conducive to the image collector to accurately detect the melt ratio information.

[0054] In one embodiment of the present invention, N=4, Figure 2 FIG. 4 shows a flow chart of a single crystal furnace full melt detection method provided by an embodiment of the present invention when N is 4. Figure 2 As shown, when N is 4, the single crystal furnace full melt detection method of the embodiment of the present invention includes the following steps:

[0055] S210, controlling the main heater and the bottom heater through the controller to heat the crucible after the silicon material is added;

[0056] S220, after the first melting time interval, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times in the first detection period, and the information is transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the first detection period is greater than or equal to the first melt ratio threshold value accounts for a proportion of the total number of detections in the first detection period that is greater than or equal to the first ratio threshold value, the first temperature adjustment strategy is executed;

[0057] S230, after the second melting time, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times in the second detection period, and the information is transmitted to the controller in real time. When the controller determines that the number of times the melt ratio of the silicon material in the second detection period is greater than or equal to the second melt ratio threshold value accounts for the total number of detections in the second detection period is greater than or equal to the second ratio threshold value, the second temperature adjustment strategy is executed;

[0058] S240, after the third melting time, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times in the third detection period, and the information is transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the third detection period is greater than or equal to the third melt ratio threshold value accounts for the total number of detections in the third detection period. The third temperature adjustment strategy is executed;

[0059] S250, after the 4th melting time, the melt ratio information of the silicon material in the crucible is collected for multiple times in the 4th detection period by controlling the image collector, and the information is transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the 4th detection period is greater than or equal to the 4th melt ratio threshold and the proportion of the total number of detections in the 4th detection period is greater than or equal to the 4th proportion threshold, the 4th temperature adjustment strategy is executed.

[0060] In this embodiment, the melting degree of the silicon material in step S210 to step S250 gradually increases, so it is necessary to execute the corresponding temperature condition strategies respectively to avoid overheating. Specifically, the power of the main heater and the bottom heater in the first temperature adjustment strategy is less than or equal to the power of the main heater and the power of the bottom heater in step S210, the rotation speed of the crucible is greater than the rotation speed of the crucible in step S210, and the height of the water cooling screen is lower than the height of the water cooling screen in step S210. In the second temperature adjustment strategy, the power of the main heater is less than or equal to the power of the main heater in the first temperature adjustment strategy, the power of the bottom heater is less than or equal to the power of the main heater and the power of the bottom heater in the first temperature adjustment strategy, the rotation speed of the crucible is greater than or equal to the rotation speed of the crucible in the first temperature adjustment strategy, and the height of the water cooling screen is lower than or equal to the height of the water cooling screen in the first temperature adjustment strategy. In the third temperature regulation strategy, the power of the main heater is less than or equal to the power of the main heater in the second temperature regulation strategy, the power of the bottom heater is less than or equal to the power of the main heater and the power of the bottom heater in the second temperature regulation strategy, the speed of the crucible is greater than or equal to the speed of the crucible in the second temperature regulation strategy, and the height of the water cooling screen is less than or equal to the height of the water cooling screen in the first temperature regulation strategy. In the fourth temperature regulation strategy, the power of the main heater is less than or equal to the power of the main heater in the third temperature regulation strategy, the power of the bottom heater is less than or equal to the power of the main heater and the power of the bottom heater in the third temperature regulation strategy, the speed of the crucible is greater than or equal to the speed of the crucible in the third temperature regulation strategy, and the height of the water cooling screen is less than or equal to the height of the water cooling screen in the third temperature regulation strategy. Therefore, the controller can control the temperature in the furnace by controlling the power of the main heater, the power of the bottom heater, the speed of the crucible and the descending height of the water cooling screen, and ensure that the silicon material in the crucible is fully melted while avoiding the crucible from being in a high temperature state for a long time, causing accidents such as silicon leakage.

[0061] When N=4, the first melt ratio threshold is 10%-15%, such as 10%, 11%, 12%, 13%, 14% or 15%. The second melt ratio threshold is 25%-35%, such as 25%, 27%, 29%, 30%, 32% or 35%. The third melt ratio threshold is 55%-75%, such as 55%, 58%, 60%, 65%, 68%, 70% or 75%. The first ratio threshold is 60%-70%, such as 60%, 64%, 68% or 70%, the second ratio threshold is 70%-80%, such as 70%, 72%, 75%, 78% or 80%, and the third ratio threshold is 85%-90%, such as 85%, 88% or 90%.

[0062] Further, when the controller controls the image collector to collect the melt ratio information of silicon materials in the first detection period, the number of melt ratios greater than or equal to 10%-15% accounts for a proportion greater than or equal to 60%-70% of the total number of detections in the first detection period, the controller executes the first temperature adjustment strategy. When the controller controls the image collector to collect the melt ratio information of silicon materials in the second detection period, the number of melt ratios greater than or equal to 25%-35% accounts for a proportion greater than or equal to 70%-80% of the total number of detections in the second detection period, the controller executes the second temperature adjustment strategy. This is because in step S220 and step S230, the range of the first melt ratio threshold and the second melt ratio threshold is small, and the temperature variation range of the crucible is also small, so that the controller can quickly execute the first temperature adjustment strategy and the second temperature adjustment strategy to adjust the temperature of the crucible as soon as possible. When the controller controls the image collector to collect the melt ratio information of the silicon material in the third detection period, and the number of melt ratios greater than or equal to 55%-75% accounts for a proportion greater than or equal to 85%-90% of the total number of detections in the third detection period, that is, the silicon material is in a semi-molten state, the controller executes the third temperature adjustment strategy. When the controller controls the image collector to collect the melt ratio information of the silicon material in the fourth detection period, and the number of melt ratios greater than or equal to 81%-100% accounts for a proportion greater than or equal to 90%-100% of the total number of detections in the fourth detection period, that is, the silicon material is in a fully molten state, the controller executes the fourth temperature adjustment strategy. Thus, the controller detects whether the proportion of the melt ratio of the silicon material in the corresponding detection period is greater than or equal to the corresponding ratio threshold to determine whether to execute the corresponding temperature adjustment strategy, which effectively improves the automation of single crystal silicon production.

[0063] In some embodiments of the present invention, the first melting time is 5-15 minutes, such as 5 minutes, 8 minutes, 10 minutes, 12 minutes or 15 minutes, etc., the second melting time is 1-3 minutes, such as 1 minute, 2 minutes or 3 minutes, etc., the third melting time is 1-3 minutes, such as 1 minute, 2 minutes or 3 minutes, etc., and the fourth melting time is 1-3 minutes, such as 1 minute, 2 minutes or 3 minutes, etc. Specifically, in steps S210-S230, most of the silicon material is still in a solid state, and the top height of the silicon material exceeds the crucible edge height of the crucible. Since the first melting time is greater than the second melting time, the third melting time and the fourth melting time, the main heater and the bottom heater can fully heat and melt the silicon material, reduce the height of the silicon material, and thus avoid interference between the silicon material and the water cooling screen when the controller lowers the water cooling screen. When the silicon material is in a semi-molten and fully molten state, the crucible is in a high-temperature state. By reducing the third melting time and the fourth melting time, the controller can quickly execute the third temperature adjustment strategy and the fourth temperature adjustment strategy, control the temperature of the silicon material more quickly, and avoid the crucible being in a high-temperature state for a long time.

[0064] In some embodiments of the present invention, the first detection period is 100-140 seconds, such as 100 seconds, 110 seconds, 120 seconds, 130 seconds or 140 seconds, etc., the second detection period is 80-120 seconds, such as 80 seconds, 90 seconds, 100 seconds, 110 seconds or 120 seconds, etc., the third detection period is 30-60 seconds, such as 30 seconds, 40 seconds, 50 seconds or 60 seconds, etc., and the fourth detection period is 30-60 seconds, such as 30 seconds, 40 seconds, 50 seconds or 60 seconds, etc. Specifically, the first detection period, the second detection period and the third detection period decrease in sequence because the silicon material is not fully melted in steps S210-S230, so the first detection period and the second detection period can be extended to ensure that the silicon material is fully melted before the silicon material is detected. When the silicon material is in a semi-molten or fully molten state, the melting process gradually stabilizes, and the third detection period can be the same as the fourth detection period, thereby shortening the detection period and improving the detection efficiency.

[0065] In one embodiment of the present invention, the water cooling screen is located at the upper limit in step S210, and the power of the main heater and the power of the bottom heater are both 85kw-96kw, such as 85kw, 88kw, 90kw, 93kw or 96kw, etc. The main heating power of the main heater and the bottom heating power of the bottom heater in step S210 can be determined according to the weight of the silicon material in the crucible during actual production.

[0066] In one embodiment of the present invention, the first temperature strategy includes: controlling the main heater and the bottom heater to heat the crucible with a first main heating power and a first bottom heating power respectively through a controller; controlling the water cooling screen to descend from an initial position to a first position at a first speed through a controller; and controlling the crucible to rotate at a first speed through a controller.

[0067] In this embodiment, when the controller is executing the first temperature strategy, the first main heating power is 85kw-96kw, and the first bottom heating power is 85kw-96kw. That is, the first main heating power and the first bottom heating power are the same as the power of the main heater and the power of the bottom heater in step S210, thereby quickly melting the silicon material in the crucible. The first rotation speed of the crucible can be 1-2 revolutions per minute, the first speed when the water-cooling screen descends is 150-250 mm per minute, and the first position of the water-cooling screen after it descends is the position where the water-cooling screen is 200-250 mm away from the silicon material liquid surface. Therefore, on the one hand, it can avoid interference between the unmelted silicon material and the water-cooling screen, and on the other hand, after the water-cooling screen descends, the image collector (such as a detection camera) arranged on the furnace cover obtains a larger field of view, thereby improving the accuracy of detection.

[0068] In one embodiment of the present invention, the second temperature strategy includes: controlling the water cooling screen to descend from the first position to the second position at a first speed through a controller; controlling the main heater and the bottom heater to continue to heat the crucible with the first main heating power and the second bottom heating power respectively through the controller; and controlling the crucible to rotate at a first speed through the controller.

[0069] In this embodiment, when the controller executes the second temperature strategy, the main heater still heats the crucible with the first main heating power, while the bottom heater decreases from the first bottom heating power to the second bottom heating power, and the second bottom heating power is 45kw-55kw. This is because in steps S210-S220, part of the silicon material has melted, so the heating power of the bottom heater can be reduced. The second position after the water cooling screen is lowered is the position where the water cooling screen is 150-200 mm away from the silicon material liquid surface, so that the crucible can be further cooled.

[0070] In one embodiment of the present invention, the third temperature strategy includes: controlling the water cooling screen to descend from the second position to the third position at a first speed through a controller; controlling the main heater and the bottom heater to continue to heat the crucible at the first main heating power and the third bottom heating power respectively through the controller; controlling the crucible to rotate at a second speed through the controller.

[0071] In step S240, the silicon material is in a semi-molten state, and the temperature of the crucible also rises accordingly, and the crucible needs to be further cooled. Therefore, when the controller executes the third temperature strategy, the main heater still heats the crucible with the first main heating power, and the bottom heater decreases from the second bottom heating power to the third bottom heating power, and the third bottom heating power is 0kw-5kw. The crucible can be increased from the first speed to the second speed, and the second speed is 2-3 revolutions per minute. The third position of the water cooling screen after it decreases at the first speed is the position where the water cooling screen is 100-150 mm away from the silicon material liquid surface.

[0072] In one embodiment of the present invention, the fourth temperature strategy includes: controlling the water cooling screen to descend from the third position to the fourth position at the second speed through the controller; controlling the main heater and the bottom heater to continue to heat the crucible at the first main heating power and the fourth bottom heating power respectively through the controller; controlling the crucible to rotate at the third speed through the controller.

[0073] In step S250, the silicon material is in a fully molten state. In order to effectively dissipate the heat of the crucible, it is necessary to further reduce the height of the water-cooled screen and the power of the bottom heater, and at the same time increase the speed of the crucible. Specifically, when the controller executes the fourth temperature strategy, the main heater still heats the crucible with the first main heating power, and the bottom heater decreases from the third bottom heating power to the fourth bottom heating power, and the fourth bottom heating power is 0kw-5kw. The crucible can be increased from the second speed to the third speed, the third speed is 3-5 revolutions per minute, the second speed of the water-cooled screen when it descends is 100-150 mm / minute, and the fourth position of the water-cooled screen after it descends at the second speed is the position of the water-cooled screen 0-100 mm away from the silicon material liquid surface. As a result, the water-cooled screen can fully take away the heat of the silicon material. In addition, since the second speed is less than the first speed, the operator can adjust the position of the water-cooled screen in time to avoid contact between the water-cooled screen and the silicon liquid.

[0074] In some embodiments of the present invention, the third bottom heating power and the fourth bottom heating power may be equal, for example, both may be 0 kW, that is, the bottom heater is in an off state, thereby effectively preventing the crucible from overheating.

[0075] In one embodiment of the present invention, the image collector is arranged on the furnace cover of the single crystal furnace and is located above the crucible and the water cooling screen. Therefore, as the water cooling screen is continuously lowered, the detection field of the image collector will also be continuously expanded, thereby effectively improving the detection accuracy.

[0076] The single crystal furnace full melt detection method of the present invention is described in detail below with reference to specific embodiments.

[0077] According to the single crystal furnace full melting detection method in the embodiment of the present invention, in step S210, after the feeding is completed, the controller will automatically turn on and control the main heater and the bottom heater to heat the silicon material in the crucible at a power of 90kw respectively to fully melt the silicon material. In step S220, after an interval of 10 minutes, the silicon material in the crucible is initially melted, and the controller can control the image collector to detect the silicon material melt ratio multiple times within 120 seconds, and when the number of times the silicon material melt ratio detected by the image collector reaches 10% accounts for 60% of the total detection times, the controller automatically executes the first temperature adjustment strategy to dissipate heat from the crucible. At this time, the controller controls the main heater and the bottom heater to continue to heat the silicon material in the crucible at a power of 90kw respectively, and at the same time controls the water cooling screen to drop from the upper limit position to a position 230 mm away from the silicon material liquid level at a speed of 200mm / min, and the controller controls the crucible to rotate at a speed of 1 revolution per minute. In step S230, after an interval of 1 minute, the controller can control the image collector to perform multiple melt ratio tests on the silicon material within 100 seconds, and when the number of times the melt ratio of the silicon material detected by the image collector reaches 30% accounts for 80% of the total number of detections, the controller executes the second temperature adjustment strategy. That is, the controller controls the water cooling screen to drop from the first position to a position 180 mm away from the silicon material liquid surface at a speed of 200 mm / min. And the controller can control the main heater to continue to operate at 90kw, and control the bottom heater to reduce from 90kw to 50kw. In addition, the controller will also control the crucible to continue to rotate at a speed of 1 revolution per minute. In step S240, after an interval of 1 minute, the controller can control the image collector to perform multiple melt ratio tests on the silicon material within 30 seconds, and when the number of times the melt ratio of the silicon material detected by the image collector reaches 60% accounts for 85% of the total number of detections, the controller executes the third temperature adjustment strategy. That is, the controller controls the water-cooling screen to drop from the second position to a position 150 mm away from the silicon material liquid surface at a speed of 200 mm / min. At the same time, the controller can control the bottom heater to reduce from 50 kW to 0 kW, that is, turn off the bottom heater, and control the main heater to continue to heat the silicon material in the crucible at a power of 90 kW. In addition, the controller also controls the crucible to rotate at a speed of 2 revolutions per minute. In step S250, after an interval of 1 minute, the controller can control the image collector to perform multiple melt ratio detections on the silicon material within 30 seconds, and when the proportion of the total number of detections of the melt ratio of the silicon material detected by the image collector reaching 81% reaches 95%, the controller executes the fourth temperature adjustment strategy. That is, the controller controls the water-cooling screen to drop from the third position to the lower limit position at a speed of 150 mm / min. At the same time, the controller can control the bottom heater to continue to be turned off, and control the main heater to continue to heat the silicon material in the crucible at a power of 90 kW. In addition, the controller also controls the crucible to rotate at a speed of 3 revolutions per minute.At this time, the main heater continues to heat the unmelted silicon material until the melt ratio of the silicon material reaches 100%. Since the bottom heater is in the off state in step S240 and step S250, and the water cooling screen is at the lower limit of the position in step S250, and the crucible rotates at a speed of 3 revolutions per minute, the crucible and the silicon material in the crucible can be fully dissipated.

[0078] In summary, the single crystal furnace full melting detection method of the embodiment of the present invention uses a controller and an image collector to detect the melting of silicon materials in the single crystal furnace, that is, the melt ratio is detected, which reduces the dependence on manual experience. At the same time, the controller can also reduce the power of the bottom heater, reduce the height of the water cooling screen, etc. when different melt ratios are reached, which can effectively reduce labor costs and avoid safety accidents caused by human errors. In addition, since automated single crystal silicon production is achieved, production efficiency can be effectively improved.

[0079] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate quantity restrictions, but indicate the existence of at least one. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship also changes accordingly.

[0080] The above are preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A single crystal furnace full melt detection method, characterized in that: The single crystal furnace comprises a crucible, a main heater, a bottom heater, an image collector and a controller, wherein the image collector is arranged on a furnace cover of the single crystal furnace and is located above the crucible. The method comprises: S1, the controller controls the main heater and the bottom heater to heat the crucible after adding silicon material; S2, after the first melting time, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times within the first detection period, and the information is transmitted to the controller in real time, and when the controller determines that the number of melt ratios of the silicon material within the first detection period is greater than or equal to the first melt ratio threshold value accounts for the total number of detections within the first detection period. The first temperature adjustment strategy is executed; ……， After the Nth melting time, the image collector is controlled to collect the melt ratio information of the silicon material in the crucible for multiple times in the Nth detection period, and the information is transmitted to the controller in real time. When the controller determines that the number of melt ratios of the silicon material in the Nth detection period is greater than or equal to the Nth melt ratio threshold and the proportion of the total number of detections in the Nth detection period is greater than or equal to the Nth proportion threshold, the Nth temperature adjustment strategy is executed, wherein N≥2, and N is an integer, the Nth melt ratio threshold is 81%-100%, and the Nth proportion threshold is 90%-100%.

2. The method according to claim 1, characterized in that The single crystal furnace further includes a water cooling screen disposed below the image collector, and the first temperature adjustment strategy, ..., and the Nth temperature adjustment strategy all include adjusting at least one of the following parameters: The power of the main heater, the power of the bottom heater, the rotation speed of the crucible and the descending height of the water cooling shield.

3. The method according to claim 2, characterized in that N=4, the first melt ratio threshold is 10%-15%, the second melt ratio threshold is 25%-35%, and the third melt ratio threshold is 55%-75%; The first ratio threshold is 60%-70%, the second ratio threshold is 70%-80%, and the third ratio threshold is 85%-90%.

4. The method according to claim 3, characterized in that The first melting time is 5-15 minutes, the second melting time is 1-3 minutes, the third melting time is 1-3 minutes, and the fourth melting time is 1-3 minutes.

5. The method according to claim 4, characterized in that The first detection period is 100-140 seconds, the second detection period is 80-120 seconds, the third detection period is 30-60 seconds, and the fourth detection period is 30-60 seconds.

6. The method according to claim 5, characterized in that The first temperature strategy includes: Controlling the main heater and the bottom heater by the controller to heat the crucible with a first main heating power and a first bottom heating power respectively; Controlling the water cooling screen to descend from an initial position to a first position at a first speed by the controller; The controller controls the crucible to rotate at a first rotation speed.

7. The method according to claim 6, characterized in that The second temperature strategy includes: Controlling the water cooling screen to descend from the first position to the second position at the first speed by the controller; Controlling the main heater and the bottom heater by the controller to continue to heat the crucible with the first main heating power and the second bottom heating power respectively; The controller controls the crucible to rotate at the first speed.

8. The method according to claim 7, characterized in that The 3rd temperature strategy includes: Controlling the water cooling screen to descend from the second position to a third position at the first speed by the controller; Controlling the main heater and the bottom heater by the controller to continue to heat the crucible with the first main heating power and the third bottom heating power respectively; The controller controls the crucible to rotate at a second rotation speed.

9. The method according to claim 8, characterized in that The 4th temperature strategy includes: Controlling the water cooling screen to descend from the third position to the fourth position at a second speed by the controller; Controlling the main heater and the bottom heater by the controller to continue to heat the crucible with the first main heating power and the fourth bottom heating power respectively; The controller controls the crucible to rotate at a third rotation speed.

10. The method according to claim 9, characterized in that In step S1, the power of the main heater and the power of the bottom heater are both 85kw-96kw; The first speed is 150-250 mm / min, and the second speed is 100-150 mm / min; The first position is a position where the water cooling screen is 200-250 mm away from the silicon material liquid surface, the second position is a position where the water cooling screen is 150-200 mm away from the silicon material liquid surface, the third position is a position where the water cooling screen is 100-150 mm away from the silicon material liquid surface, and the fourth position is a position where the water cooling screen is 0-100 mm away from the silicon material liquid surface; The first main heating power is 85kw-96kw, the first bottom heating power is 85kw-96kw, the second bottom heating power is 45kw-55kw, the third bottom heating power is 0kw-5kw, and the fourth bottom heating power is 0kw-5kw; The first rotation speed is 1-2 revolutions per minute, the second rotation speed is 2-3 revolutions per minute, and the third rotation speed is 3-5 revolutions per minute.

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